1. Field of the Invention
The present invention relates to a water pump for an internal combustion engine. More particularly, the present invention relates to erosion and water leakage prevention for a water pump for an internal combustion engine.
2. Description of the Prior Art
A lot of water pumps for an internal combustion engine have been proposed so far. For instance, a water pump is disclosed in Japanese Examined Utility Model Publication (KOUKOKU) No. 28319/1989, and will be hereinafter described with reference to FIG. 6. The water pump 60 includes a pump body 61, a pump cover 62, a volute chamber 63 formed in the pump body 61 and the pump cover 62, a driving shaft 65 held rotatably in the pump body 61 by way of a bearing 64, and a mechanical seal 66 disposed on the driving shaft 65 between the volute chamber 63 and the bearing 64. The pump body 61 and the pump cover 62 are separate and divided component parts, and are usually formed of an aluminum material.
Further, a pulley 67 is fixed on an end of the driving shaft 65 so as to input a driving force to the driving shaft 65. Furthermore, an impeller 68 is fixed on the opposite end of the driving shaft 65. Moreover, a chamber 69 is formed in an annular shape in the pump body 61 on a back side of the impeller 68 so as to inhibit the pump body 61 from being failingly cast.
There are foreign matters (for instance, casting sands or the like having been left in the cylinder block of an engine) contained in a coolant. The foreign matters flow together with the coolant in a coolant circuit (not shown) into which the above-described conventional water pump 60 is disposed. When the foreign matters intrude into the chamber 69, the foreign matters are kept circulating in the chamber 69 together with the coolant flowing therein. As a result, the foreign matters gradually erode the wall surface of the pump body 61 away. Finally, there might be a fear for communicating the inside of the pump body 61 with the outside, and accordingly the coolant in the volute chamber 63 might leak to the outside.